Step-by-step explanation:
<em>I think you have forgotten to attach the question. </em>
<em>Anyways....</em>
In order to find the area of a circle use the formula:
π
Where r is the radius
For example the radius is 3cm. The area of the circle will be:
π × 
Since you have taken pi as 3.142...
3.142 × 
3.142 × 9
= 28.278
In order to find the answer to 1 decimal place, check the number next to the number right after the decimal. Is it a number greater than or equal to 5? then add +1 to the number.
= 28.3 
Answer:
90 g of water should be added and he will make 900 g of solution.
Step-by-step explanation:
Let x g be the amount of salt Ilya add to 810g of water to make 10% solution. Then 810+x g is the amount of new solution. Thus,
810+x - 100%,
x - 10%.
Mathematically,

So 90 g of water should be added and he will make 810+90=900 g of solution.
The answer is: idk I came here to get points lol